#include "ModbusUtil.h"

//********************************************************************
// FUCTION: Modbus_CRC16 —— MODBUS RTU CRC16校验生成函数
// VERSION: 1	(2010-9-27 14:34:01)
// INPUT:	dat_buf 待校验数值缓存区
// 			dat_len 待校验数值缓存区的长度
// OUTPUT:	CRC16校验值
// EXAMPLE:
// 输入数据 dat_buf指向的数组为： 0x33, 0x78, 0x98, 0x60, 校验长度为4
// 则输出为：高字节0xE4 低字节0x91
//********************************************************************
quint16 CModbusUtil::Modbus_CRC16(uchar *dat_buf,uchar dat_len) //ScuBch
{
    /* CRC 高位字节值表 */
    const uchar AUCHCRCHI[256]=
        {
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x00,0x0C1,0x81,0x40,0x01,0x0C0,0x80,0x41,
            0x01,0x0C0,0x80,0x41,0x00,0x0C1,0x81,0x40
        };

    /* CRC 低位字节值表 */
    const uchar AUCHCRCLO[256]=
        {
            0,0xC0,0xC1,0x01,0xC3,0x03,0x02,0xC2,
            0xC6,0x06,0x07,0xC7,0x05,0xC5,0xC4,0x04,
            0xCC,0x0C,0x0D,0xCD,0x0F,0xCF,0xCE,0x0E,
            0x0A,0xCA,0xCB,0x0B,0xC9,0x09,0x08,0xC8,
            0xD8,0x18,0x19,0xD9,0x1B,0xDB,0xDA,0x1A,
            0x1E,0xDE,0xDF,0x1F,0xDD,0x1D,0x1C,0xDC,
            0x14,0xD4,0xD5,0x15,0xD7,0x17,0x16,0xD6,
            0xD2,0x12,0x13,0xD3,0x11,0xD1,0xD0,0x10,
            0xF0,0x30,0x31,0xF1,0x33,0xF3,0xF2,0x32,
            0x36,0xF6,0xF7,0x37,0xF5,0x35,0x34,0xF4,
            0x3C,0xFC,0xFD,0x3D,0xFF,0x3F,0x3E,0xFE,
            0xFA,0x3A,0x3B,0xFB,0x39,0xF9,0xF8,0x38,
            0x28,0xE8,0xE9,0x29,0xEB,0x2B,0x2A,0xEA,
            0xEE,0x2E,0x2F,0xEF,0x2D,0xED,0xEC,0x2C,
            0xE4,0x24,0x25,0xE5,0x27,0xE7,0xE6,0x26,
            0x22,0xE2,0xE3,0x23,0xE1,0x21,0x20,0xE0,
            0xA0,0x60,0x61,0xA1,0x63,0xA3,0xA2,0x62,
            0x66,0xA6,0xA7,0x67,0xA5,0x65,0x64,0xA4,
            0x6C,0xAC,0xAD,0x6D,0xAF,0x6F,0x6E,0xAE,
            0xAA,0x6A,0x6B,0xAB,0x69,0xA9,0xA8,0x68,
            0x78,0xB8,0xB9,0x79,0xBB,0x7B,0x7A,0xBA,
            0xBE,0x7E,0x7F,0xBF,0x7D,0xBD,0xBC,0x7C,
            0xB4,0x74,0x75,0xB5,0x77,0xB7,0xB6,0x76,
            0x72,0xB2,0xB3,0x73,0xB1,0x71,0x70,0xB0,
            0x50,0x90,0x91,0x51,0x93,0x53,0x52,0x92,
            0x96,0x56,0x57,0x97,0x55,0x95,0x94,0x54,
            0x9c,0x5c,0x5d,0x9d,0x5f,0x9f,0x9e,0x5e,
            0x5a,0x9a,0x9b,0x5b,0x99,0x59,0x58,0x98,
            0x88,0x48,0x49,0x89,0x4b,0x8b,0x8a,0x4a,
            0x4e,0x8e,0x8f,0x4f,0x8d,0x4d,0x4c,0x8c,
            0x44,0x84,0x85,0x45,0x87,0x47,0x46,0x86,
            0x82,0x42,0x43,0x83,0x41,0x81,0x80,0x40
        };

    uchar j,CH,CL;
    quint16 i;
    CH = 0XFF;
    CL = 0XFF;
    for (i = 0; i < dat_len; i++)
    {
        j = dat_buf[i];
        j = CH ^ j;
        CH = CL ^ AUCHCRCHI[j];
        CL = AUCHCRCLO[j];
    }

    return(CH * 0x100 + CL);
}
